Method of manufacturing printing plate and method of manufacturing liquid crystal display device using the same

ABSTRACT

A method of manufacturing a precise printing plate, and a method of manufacturing an LCD device using the same are disclosed, the method of manufacturing the precise printing plate comprising forming a mask layer of a predetermined pattern on a substrate; etching the substrate with an etchant including an anionic surfactant by using the mask layer of the predetermined pattern, to thereby form a trench; and removing the mask layer.

The present patent document is a divisional of U.S. patent applicationSer. No. 11/479,001, filed Jun. 29, 2006, which claims priority toKorean Patent Application No. P2005-111227, filed on Nov. 21, 2005,which is hereby incorporated by reference as if fully set forth herein.

BACKGROUND

1. Technical Field

The present invention relates to a liquid crystal display (LCD) device,and more particularly, to a method of manufacturing a printing plateused for a printing method which is one of patterning methods, and amethod of manufacturing an LCD device using the same.

2. Discussion of the Related Art

Among various ultra-thin flat type display devices, which include adisplay screen having a thickness of several centimeters, a liquidcrystal display (LCD) device can be widely used for notebook computers,monitors, aircraft, and etc. since it has advantages such as low powerconsumption and portability.

The LCD device includes lower and upper substrates facing each other ata predetermined interval therebetween, and a liquid crystal layer formedbetween the lower and upper substrates.

The lower substrate comprises a gate line, a data line, and a thin filmtransistor. At this time, the gate line is formed in perpendicular tothe data line, to define a unit pixel region. Then, the thin filmtransistor is formed adjacent to a crossing of the gate and data lines,wherein the thin film transistor serves as a switching device. Inaddition, a pixel electrode is connected with the thin film transistor.

The upper substrate comprises a black matrix layer for shielding thegate line, the data line and the thin film transistor from light, acolor filter layer formed on the black matrix layer, and a commonelectrode or an overcoat layer formed on the color filter layer.

The above LCD device includes various elements formed by repeated steps.Especially, a photolithography is used so as to form the elements invarious shapes.

For the photolithography, it is necessary to form a pattern materiallayer on a substrate, to deposit a photoresist on the pattern materiallayer, to position a mask of a predetermined pattern above thephotoresist, and to pattern the photoresist according to thepredetermined pattern of the mask by exposure and development. Afterthat, the pattern material layer is etched using the patternedphotoresist as a mask.

The photolithography necessarily uses the photoresist and the mask ofthe predetermined pattern, to thereby increase a manufacturing cost. Inaddition, since the photolithography requires exposure and development,it causes a complicated process and an increasing manufacturing time.

To overcome these problems of the photolithography, a new patterningmethod has been developed, for example, a printing method using aprinting roller.

A patterning method using a printing roller according to the related artwill be described with reference to the accompanying drawings.

FIGS. 1A to 1C are cross sectional views of illustrating a process forpatterning a predetermined material on a substrate with a printingroller according to the related art.

As shown in FIG. 1A, first, a pattern material 30 is provided through aprinting nozzle 10, and is coated on a printing roller 20.

Then, as shown in FIG. 1B, the printing roller 20 coated with thepattern material 30 rolls on a printing plate 40 having a plurality ofconcave and convex patterns. Accordingly, some pattern material 30 b isprinted on the convex patterns of the printing plate 40, and the otherpattern material 30 a is left on the printing roller 20. That is, apredetermined form of the pattern material is formed on the printingroller 20.

Referring to FIG. 1C, as the printing roller 20 having the patternmaterial of the predetermined pattern rolls on a substrate 50, thepattern material 30 a is printed on the substrate 50.

The patterning method using the printing roller requires the printingplate having the predetermined concave and convex patterns.

A method for manufacturing a printing plate according to the related artwill be described as follows.

FIGS. 2A to 2C are cross sectional views of illustrating a method formanufacturing a printing plate according to the related art.

As shown in FIG. 2A, a metal layer 60 is formed on a substrate 45. Then,a photoresist 61 is formed on the metal layer 60. Thereafter, thephotoresist 61 is patterned by exposure and development. Then, the metallayer is selectively removed using the patterned photoresist 61 as amask, to thereby form a mask layer 60 a of a predetermined pattern.

Referring to FIG. 2B, after removing the photoresist 61, the substrate45 is isotropically etched using the mask layer 60 a, to thereby form atrench 70 in the substrate 45. At this time, the substrate 45 is etchedin the isotropic method of wet-etching. Accordingly, some portions ofthe substrate 45 under the mask layer 60 a may be removed since thesubstrate 45 is etched in a horizontal direction as well as in avertical direction, thereby generating an undercut phenomenon.

Referring to FIG. 2C, the mask layer 60 a is removed to thereby form aprinting plate 40.

However, the method of manufacturing the printing plate according to therelated art has the following disadvantages.

FIG. 3 is a cross sectional view of explaining a problem generated whenforming the pattern with the printing plate according to the relatedart.

As explained in FIG. 2B, when forming the trench 70, the substrate 45 isisotropically etched. That is, the substrate 45 is etched in thehorizontal direction as well as in the vertical direction, whereby theinner side surface of the trench 70 has a gentle slope.

Accordingly, when printing the pattern material 30 b on the printingplate 40, the pattern material 30 b is printed on the edges and innersurfaces of the trench 70. That is, it is difficult to print theprecisely desired pattern on the printing roller 20.

SUMMARY

Accordingly, the present invention is directed to a method ofmanufacturing a precise printing plate, and a method of manufacturing anLCD device using the same, which substantially obviates one or moreproblems due to limitations and disadvantages of the related art.

Additional advantages, and features of the invention will be set forthin part in the description which follows and in part will becomeapparent to those having ordinary skill in the art upon examination ofthe following or may be learned from practice of the invention. Theadvantages of the invention may be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described herein, a method formanufacturing a printing plate includes forming a mask layer having atleast one opening on a substrate. The substrate is etched with anetchant including an anionic surfactant by using the mask layer as amask to thereby form at least one trench. After forming the trench, themask layer is removed.

In another aspect of the present invention, a method for manufacturingan LCD device includes preparing a at least one printing plate havingconcave or convex patterns formed by selectively etching a platesubstrate with an etchant including an anionic surfactant. A blackmatrix layer is formed on a first substrate and a color filter layer isformed on the first substrate an a portion of the black matrix layer.The first substrate and a second substrate are bonded to each other at apredetermined interval therebetween. One or both of the black matrixlayer and the color filter layer are formed using the printing plate. Inanother aspect of the present invention, a method for manufacturing anLCD device comprises preparing at least one printing plate havingconcave or convex portions formed by selectively etching a substratewith an etchant including an anionic surfactant; forming a materiallayer on a TFT substrate, the material layer configured to form acomponent of the TFT substrate; forming a photoresist pattern on thematerial layer using the at least one printing plate; and forming thecomponent by etching the material layer using the photoresist pattern asan etching mask.

In yet another aspect of the invention, a method for manufacturing aprinting plate includes providing a plate substrate and forming a metalmask layer having at least one opening on a plate substrate. Thesubstrate is etched with an etchant including an anionic surfactantusing the metal mask layer as an etch mask, to thereby form at least onetrench. The anionic surfactant adheres to the metal mask during etchingand the metal mask layer is removed after the etching process.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIGS. 1A to 1C are cross sectional views of illustrating a process forpatterning a predetermined material on a substrate with a printingroller according to the related art;

FIGS. 2A to 2C are cross sectional views of illustrating a method formanufacturing a printing plate according to the related art;

FIG. 3 is a cross sectional view of illustrating a problem generatedwhen forming a predetermined pattern using a printing plate according tothe related art;

FIGS. 4A to 4C are cross sectional views of illustrating a process formanufacturing a printing plate according to the present invention;

FIGS. 5A to 5D are cross sectional views of illustrating a method formanufacturing an LCD device according to the present invention; and

FIGS. 6A to 6C are cross sectional views of illustrating a process forpatterning a predetermined material using a printing plate according tothe present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

Hereinafter, a method for manufacturing a printing plate and a methodfor manufacturing an LCD device according to the present invention willbe described with reference to the accompanying drawings.

FIGS. 4A to 4C are cross sectional views illustrating a method formanufacturing a printing plate according to the present invention.

First, as shown in FIG. 4A, a metal layer 600 is formed on a substrate450, and a photoresist 610 is formed on the metal layer 600. Then, thephotoresist 610 is patterned by exposure and development. Thereafter,the metal layer 600 is selectively removed using the patternedphotoresist 610 as a mask, thereby forming a mask layer 600 a having atleast one opening. The metal layer 600 may be formed in a single-layeredor dual-layered structure using chrome Cr, molybdenum Mo, copper Cu, orindium-tin-oxide (ITO).

As shown in FIG. 4B, after removing the photoresist 610, the substrate450 is isotropically etched with an etchant including an anionicsurfactant 800 by using the mask layer 600 as an etching mask, tothereby form at least one trench 700 in the substrate 450. That is, theetchant may be a fluoric acid (HF) solution including the anionicsurfactant 800, or a mixture of a ammonium fluoride (NH₄F) and a fluoricacid (HF) solution including the anionic surfactant 800, for etching ofthe substrate 450.

As the anionic surfactant 800 is in contact with the exposed portion ofthe metal mask layer 600 a, the anionic surfactant 800 is adhered ontothe surface of the mask layer 600 by positive charges induced in thesurface of the mask layer 600 a. Accordingly, it is possible to preventhorizontal etching in the substrate 450.

As shown in FIG. 4C, the mask layer 600 a is removed to thereby form aprinting plate 400. That is, the trench is formed in the predeterminedportion of the substrate, whereby the printing plate has concave orconvex pattern.

That is, the substrate 450 is etched by the etchant including theanionic surfactant 800. Accordingly, since the anionic surfactant 800adheres to the exposed portions of the metal mask layer 600 a, the sideslope of the trench formed in the substrate 450 is nearly vertical. As aresult, in case of printing the pattern material on the printing plate,the pattern material is not printed on the edge and inner surfaces ofthe trench 700, to thereby obtain the precise pattern.

A method for manufacturing an LCD device using the printing plateaccording to the present invention will be described as follows.

FIGS. 5A to 5D are cross sectional views of illustrating a method formanufacturing an LCD device according to the present invention. FIGS. 6Ato 6C are cross sectional views of illustrating a method for forming ablack matrix layer or a color filter layer of an LCD device with aprinting plate according to the present invention.

As shown in FIG. 5A, a black matrix layer 330 is formed on a firstsubstrate 500 of a color filter array substrate. At this time, the blackmatrix layer 330 is provided to prevent a light from leaking in otherportions except pixel regions.

As shown in FIG. 5B, a color filter layer 350 is formed on the firstsubstrate 500 including the black matrix layer 330. At this time, atleast one of steps for forming the black matrix layer 330 (FIG. 5A) andforming the color filter layer 350 (FIG. 5B) uses the above-mentionedprinting plate, so as to form the black matrix layer 330 or/and colorfilter layer 350.

That is, a preferable method for forming the pattern with theabove-mentioned printing plate will be explained with reference to FIGS.6A to 6C.

As shown in FIG. 6A, a pattern material 300 (for example, a lightshielding material or a color filter material) is supplied through aprinting nozzle 100, and is coated on a printing roller 200.

Referring to FIG. 6B, the printing roller 200 coated with the patternmaterial 300 rolls on the printing plate 400 manufactured by theabove-mentioned method, so as to print some pattern material 300 b onthe convex patterns of the printing plate 400 and to leave a remainingpattern material.

As shown in FIG. 6C, the printing roller 200 rolls on the substrate 500,so as to print the remaining pattern material 300 a on the substrate500.

According to the method of FIGS. 6A to 6C, the black matrix layer 330or/and color filter layer 350 is formed on the substrate 500.

A patterning method using the printing plate manufactured by the abovemethod according to the preferred embodiment of the present inventionmay be applied to a step for preparing a second substrate 550.

Referring back to FIG. 5C, the second substrate 550 is prepared.Although not shown, and as is known in the art, the second substrate 550is comprised of gate and data lines crossing each other to define a unitpixel region, a thin film transistor TFT formed adjacent to a crossingof the gate and data lines, and a pixel electrode formed in the pixelregion and connected with the thin film transistor TFT.

In accordance with an embodiment, all elements of the TFT substrateincluding the gate lines, data lines, pixel electrodes, active layers,and passivation layer of the TFT substrate can be formed using a form ofthe process illustrated in FIGS. 6A-6C. For example, at least one ofmore elements on the TFT substrate, an additional substrate isfabricated having the features shown in substrate 400.

In order to form the features of the TFT substrate, a printing plate isformed using the process described above. The dimensions of thestructures on the printing plate are changed from that shown for thecolor filter process to accommodate the feature sizes of the data lines,gate lines, pixel electrodes, and the like on the TFT substrate. Theprocess is carried out using the steps shown in FIGS. 6A-6C, but theprinting plate is configured for the feature sizes of the variouscomponents in the TFT substrate.

For example, a method for forming the gate lines using the printingplate according to the present invention will now be described.

A metal layer for forming the gate lines is formed on the secondsubstrate 550. A photoresist is provided through a printing nozzle, andis coated on a printing roller.

Then, the printing roller having the photoresist coated thereon rolls ona printing plate for patterning the gate lines as shown in FIG. 6A or6B, whereby the photoresist is printed on the printing plate forpatterning the gate lines and the photoresist remains on the printingroller.

As the printing roller rolls on the second substrate 550 including themetal layer, and the remaining photoresist on the printing roller isprinted onto the metal layer as shown FIG. 6 c.

The metal layer is selectively removed by etching the metal layer usingthe photoresist as a mask, to thereby form the gate lines.

According to the method shown in FIGS. 6A to 6C, a photoresist may becoated on the printing roller 200, to thereby form the photoresistpattern for forming the data lines, the pixel electrodes, the activelayers, or the passivation layer on the second substrate 550.

Therefore, the illustrative embodiment of the present inventionadvantageously does not use a photolithography process.

As shown in FIG. 5C, the second substrate 550 of a thin film transistorarray substrate is provided in opposite to the first substrate 500.

Although not shown, but as known to those skilled in the art, the secondsubstrate 550 includes gate and data lines crossing each other to definea pixel region, a thin film transistor formed adjacent to a crossing ofthe gate and data lines, and a pixel electrode connected with the thinfilm transistor.

After that, as shown in FIG. 5D, the first and second substrates 500 and550 are bonded to each other at a predetermined intervals therebetween,and a liquid crystal layer 900 is formed between the first and secondsubstrates 500 and 550.

At this time, the liquid crystal layer 900 may be formed in a dispensingmethod or an injection.

When applying the dispensing method, a sealant having no inlet is formedin any one of the first and second substrates, and liquid crystal isdispensed on any one of the first and second substrates, and then thetwo substrates are bonded to each other.

Alternatively, in the case of applying the injection method, afterbonding the two substrates with a sealant having an inlet, liquidcrystal is injected to a space between the first and second substratesby capillary phenomenon and pressure difference.

As mentioned above, the method for manufacturing the printing plate andthe method for manufacturing the LCD device according to the presentinvention have the following advantages.

To manufacture the printing plate, after the metal mask layer is firstlyformed, the substrate is etched by the etchant comprising the anionicsurfactant. Accordingly, the anionic surfactant is adhered to theexposed portion of the mask layer, so that it is possible to prevent theetching of horizontal direction in the substrate. As a result, thenarrow and deep trench can be formed in the printing plate, to therebyform the precise pattern. Especially, the above method of the presentinvention is useful to manufacture the thin film transistor requiringthe precise pattern.

Also, the side surface of the trench has the gentle slope which isnearly horizontal. Accordingly, it is possible to prevent the patternmaterial from being printed on the edge and inner surface of the trench,to thereby form the precise pattern. The above method substitutes forthe expensive photolithography, thereby decreasing the manufacturingcost.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method for manufacturing a liquid crystal display devicecomprising: preparing at least one printing plate having concave orconvex portions, wherein the step of preparing the printing platecomprises: sequentially forming a metal layer and a photoresist on asubstrate; patterning the photoresist by exposure and development;etching the metal layer using the patterned photoresist as an etch mask,to thereby form a mask layer having the concave or convex portions;removing the patterned photoresist; etching the substrate with anetchant including an anionic surfactant using the mask layer as an etchmask, to thereby form at least one trench, wherein the anionicsurfactant is adhered to a surface of the mask layer so that the anionicsurfactant prevents the at least one trench from being etchedhorizontally; and removing the mask layer; forming a black matrix layeron a first substrate; forming a color filter layer on the firstsubstrate and on a portion of the black matrix layer; and bonding thefirst substrate and a second substrate to each other at a predeterminedinterval therebetween, wherein at least one of the black matrix layerand the color filter layer is formed using the at least one printingplate.
 2. The method of claim 1, wherein forming a black matrix layerusing the at least one printing plate comprises: coating alight-shielding material on a printing roller; rolling the printingroller on the printing plate, so as to print a portion of thelight-shielding material on the convex portions of the printing plateand to leave a remaining portion on the printing roller; and rolling theprinting roller on the first substrate, so as to print the remainingportion of light-shielding material on the first substrate.
 3. Themethod of claim 1, wherein the process of forming the color filter layerusing the at least one printing plate comprises: coating a color filtermaterial on the printing roller; rolling the printing roller on the atleast one printing plate, so as to print a portion of the color filtermaterial on the convex portion of the at least one printing plate and toleave a remaining portion on the printing roller; and rolling theprinting roller on the first substrate, so as to print the remainingportion on the first substrate.
 4. The method of claim 1, wherein thesecond substrate comprises gate and data lines crossing each other todefine a pixel region, a thin film transistor formed adjacent to acrossing of the gate and data lines, and a pixel electrode electricallyconnected with the thin film transistor in the pixel region.
 5. Themethod of claim 1, further comprising: forming a sealant having no inletto any one of the first and second substrates before bonding the firstand second substrates to each other; and dispensing liquid crystal ontoone of the first and second substrates.
 6. The method of claim 1,further comprising forming a liquid crystal layer between the first andsecond substrates after bonding the first and second substrates to eachother.
 7. A method for fabricating liquid crystal display devicecomprising: preparing at least one printing plate having concave orconvex portions, wherein the step of preparing the printing platecomprises: sequentially forming a metal layer and a photoresist on asubstrate; patterning the photoresist by exposure and development;etching the metal layer using the patterned photoresist as an etch mask,to thereby form a mask layer having the concave or convex portions;removing the patterned photoresist; etching the substrate with anetchant including an anionic surfactant using the mask layer as an etchmask, to thereby form at least one trench, wherein the anionicsurfactant is adhered to a surface of the mask layer so that the anionicsurfactant prevents the at least one trench from being etchedhorizontally; and removing the mask layer; forming a material layer on afirst substrate, the material layer configured to form at least onecomponent of the first substrate, wherein the component of the firstsubstrate includes gate and data lines crossing each other to define apixel region, a thin film transistor formed adjacent to a crossing ofthe gate and data lines, and a pixel electrode connected with the thinfilm transistor; forming a photoresist pattern on the material layerusing the at least one printing plate; and forming the component byetching the material layer using the photoresist pattern as an etchingmask.
 8. The method of claim 7, wherein the process of forming thephotoresist pattern on the material layer using the at least oneprinting plate comprises: coating a photoresist material on a printingroller; rolling the printing roller on the printing plate, so as toprint a portion of the photoresist material on the convex portions ofthe printing plate and to leave a remaining portion on the printingroller; and rolling the printing roller on the first substrate, so as toprint the remaining portion of the photoresist material on the firstsubstrate.